I asked this over in the DynoFlash forum, but thought I'd ask everyone else also....

How much average do you see HP loss with a HF cat over a testpipe, considering a 3" exhaust from the turbo back?

Anyone have any dyno's? Im debating putting on my 3" HF cat (Magnaflow) to quiet down my car, but I don't want it to feel slow.

BTW, I searched, but couldn't find anything concrete except that DynoFlash said with the 3" UR HF cat, he didn't lose even 1 hp here:

https://www.evolutionm.net/forums/sh...ad.php?t=55371

the UR HF cat uses the magnaflow converter, right? Why did DynoFlash say he gained low end? Backpressure? I thought the testpipe increases everything, even low end.

Thanks for the input.

 

3-5 whp lost over a cat delete

 

I would say 5-10 whp. I dynoed at 290 with a 3inch cat.

 

If you look in the thread I posted above, DynoFlash claims he lost zero hp with a UR HF Cat.

 

Anyone happen to have any dyno graphs with nothing changed but the HF Cat and testpipe?

 

I dynoed with a high flow cat and without. It was somewhere between 12-15 HP. No other changes. No joke. Sorry I don't have a scanner to post the graphs. Both runs were done at Turbo Trix.

 

Did your boost go up when you dyno'd with the testpipe? I wonder if some of that horsepower was due to increased boost since less backpressure.

 

will there will be a increase in boost since and the exhaust gases and flowing alot faster gains will be more depending on mods but hp range is from 5-10 hp

 

Also depends on how good the cat is. I had a noticeable bump switching from the Buschur cat to a Random Tech. Still not like a test pipe but closer.

 

With a Random Tech 3" high flow cat, you can't tell a difference when you switch to the test pipe. I have run with the testpipe on and then switched to the RT cat and couldn't tell a difference at all in just driving the car. In fact, my RT 3" cat still throws a CEL if you dont do the anti spark plug fouler trick. It is very high flow. No loss in boost pressure when switching to the high flow cat either. I am sure there is a measureable difference on the dyno, but the butt dyno will never detect it. My $.02 !!!!

Brian

 

What about a Helix High Flow Cat vs. Helix Test Pipe ?

 

I don't see how they consider the Helix HF Cat a cat at all.

 

Why ?

 

Bump

 

I have the RT HF Cat as well, and I also required a single drilled (to 1/2 inch) spark plug anti-fouler to get rid of the CEL.

If you look at it, it looks like a resonator more than a cat, lol. Noticed better spool and top-end with a little more noise after swapping it in. The RT has a CARB sticker, so I would think it could pass emissions, but I haven't had to prove it yet. I think as long as I don't have a CEL they don't even smog it here in MA. Someone please correct me if I'm wrong.

Take care,

FB